Spinner assembly for model airplanes

ABSTRACT

A spinner assembly is provided for model airplanes which is particularly suited for engagement by a starter motor for starting the airplane engine. In order to reduce the stress and strain on the nose cap and propeller resulting from the use of starter motors, the inner surface of the nose cap is provided with a cylindrical flange for frictionally engaging the shoulder portion of the inner of two nuts which holds the propeller on the propeller shaft. In this manner some of the torque or rotational force imparted by the starter motor is transmitted to the propeller shaft through the stronger portions of the nose cap instead of through the weaker outer periphery of the nose cap and the propeller itself. The nose cap is preferably fastened to the propeller shaft and tightened against the shoulder of the inner or first nut by means of a screw through the apex of the nose cap and into the cap of a second or lock nut which secures the propeller on the shaft.

United States Patent Sullivan Aug. 26, 1975 SPINNER ASSEMBLY FOR MODELPrimary ExaminerEverette A. Powell, Jr. AIRPLANES Attorney, Agent, orFirm-Seidel, Gonda & 75 Inventor: Matthew A. Sullivan, Elkins Park,Gddhamme Pa. [57] ABSTRACT [73] Ass1gnee: Sullivan Products, Inc.,WlllOW Grove Pa A spinner assembly is provided for model airplanes whichis particularly suited for engagement by a 2] Filed: July 17, 1974starter motor for starting the airplane engine. In order [21] Appl No:489,319 to reduce the stress and strain on the nose cap and propellerresulting from the use of starter motors, the inner surface of the nosecap is provided with a cylin- [52] US. Cl. 416/245 drical flange forfrictionally engaging the shoulder B64C 11/14 portion of the inner oftwo nuts which holds the proof Search pener on the propeller shaft Inmanner some of the torque or rotational force imparted by the startermotor is transmitted to the propeller shaft through the [56] ReferencesCited stronger portions of the nose cap instead of through UNITED STATESPATENTS the weaker outer periphery of the nose cap and the 1,382,836 61921 .Iuclson 1. 416/208 pgopener g 3 i g l f fi 1,668,972 5/1928McCauley 416/245 t e Pro?e er 5 a 1% agamst t e s 2270575 H1942 Bahr416/245 X of the inner or first nut by means of a screw through 370334111/1972 Garofak, 41 245 the apex of the nose cap and into the cap of asecond 3 822 963 7/1974 Goldber l. 416/245 0r lock nut which secures thepropeller on the shaft.

12 Claims, 3 Drawing Figures 32 62\ 44 38 :III: 46 i I /0\ 54 55 24 /4 EEZ J 58 I 1 ,j T1 50 1,1. m. .|.|.n l .55 52 [/8 SPINNER ASSEMBLY FORMODEL AIRPLANES BACKGROUND OF THE INVENTION The present inventionrelates to spinner assemblies for model airplanes. More particularly,the present invention is directed to spinner assemblies which arespecially suited for use in connection with starter motors for startingmodel airplane engines.

For a number of years now it has been popular among model airplaneenthusiasts to use starter motors for starting the engines of modelairplanes. Such starter motors generally comprise a motor driven shafthaving a rotating cup attached to the end thereof. The cup is placed infrictional engagement with the spinner or nose cap of the modelairplane, whereby the torque of the starter motor is transmitted to thepropeller shaft of the airplane to start the airplane engine. Examplesof such starter motors are disclosed in U.S. Pat. Nos. 2,475,750 and2,625,143, as well as my copending application Ser. No. 489,318, filedJuly 17, 1974, entitled Housing For Starter Motor.

In order for the spinner to transmit the torque from the starter motorto the propeller shaft, there must be some connection or engagement ofthe spinner with ei ther the shaft itself or the propeller. It has beenknown for some time to cut notches in the rear edge of the spinner inorder for the spinner to engage the blades of the propeller. Examples ofsuch spinners having notches are illustrated in U.S. Pat. Nos.2,559,882; 2,674,063; 2,765,858 and 3,703,341. It has also been knownfor some time to attach the spinner to the shaft by means of a screw atthe front or apex of the spinner, which screw is connected to the shaftby means of an adapter. Examples of such arrangements are illustrated inU.S. Pat. Nos. 2,534,662 and 2,559,882.

The use of notches in the nose cap or spinner to transmit the torque ofthe starter motor to the propeller shaft has its disadvantages in thatthe periphery of the nose cap where the notches are located is theweakest part of the nose cap. Accordingly, undue stress and strain maybe placed on these portions of the nose cap, as well as the blades ofthe propeller. The screw joining the nose cap or spinner to thepropeller shaft is similarly unsuited for absorbing the entire torquefrom the starter motor, and in fact the spinner or nose cap may simplyturn under the screw without transmitting the torque to the propellershaft, unless some means is provided to positively lock the screw andnose cap to prevent relative rotation.

Accordingly, it would be desirable to have a spinner or nose capassembly which will transmit the torque of the starter motor to thepropeller shaft without exerting undue stress or strain on the propellerblades, the periphery of the nose cap or the fastening means for thenose cap.

BRIEF SUMMARY OF THE INVENTION The above and other disadvantages of theprior art are alleviated by the apparatus of the present invention whichrelates to spinner assemblies for attachment to the threaded propellershaft of a model airplane comprising a propeller, a generally conicalhollow nose cap and two threaded nuts for fastening the propeller to theshaft, the first nut abutting against the propeller hub and the secondnut locking the first nut in place. The improvement comprises providingthe spinner assembly with flange means extending from the interiorsurface of the nose cap and shoulder means on the first threaded nut,such that the flange means frictionally engages the shoulder means whenthe nose cap is in operating position.

Preferably, the nose cap is connected to the propeller shaft by a screwwhich passes through the front or apex of the nose cap and is threadedinto the cap of the second or lock nut. Tightening of the screw not onlysecures the nose cap but also forces the flange means of the nose capinto frictional engagement with the shoulder means of the first nut.

BRIEF DESCRIPTION OF THE DRAWINGS For the purpose of illustrating theinvention, there is shown in the drawings a form which is presentlypreferred; it being understood, however, that this invention is notlimited to the precise arrangements and instrumentalities shown.

FIG. 1 is a side elevation view, mostly in section, il lustrating thespinner assembly of the present invention.

FIG. 2 is an exploded perspective view of the various parts whichcomprise the spinner assembly of the present invention.

FIG. 3 is a sectional view of the spinner assembly of the presentinvention taken along line 33 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thedrawings wherein like reference numerals refer to like elementsthroughout the three figures, there is illustrated a spinner assembly,generally indicated as 10. The spinner assembly 10 comprises a propeller12, a propeller shaft 14 and a nose cap or cowling 16.

The propeller 12 comprises a hub portion 18, lying generally within nosecap 16, and blade portions 20, which extend beyond the outer peripheryof the nose cap 16. Although the propeller 12 shown in the drawings hasonly two blades 20, it will be understood that the propeller may haveany number of blades desired, such as three or four blades, as known inthe art.

The hub 18 of propeller 12 is provided with a hole 22 for mounting thepropeller 12 on propeller shaft 14. Shaft 14 is provided with a threadedend portion 24, and propeller 12 is mounted thereon by sliding thethreaded portion 24 through hole 22 and screwing first and secondthreaded nuts, 26 and 28 respectively, onto the threaded portion 24. Thefirst threaded nut 26, which will be referred to as the starter nut,abuts against the hub 18 of propeller 22, while the second threaded nut28, which will be referred to as the lock nut, abuts against theopposite side of starter nut 26 and locks the starter nut 26 in place.That is, lock nut 28 prevents starter nut 26 from being backed offwithout first loosening lock nut 28.

The nose cap 16 comprises a hollow, thin-walled, generally conicalmember which covers or encloses the remainder of the spinner assemblyexcept for the blade portions 20 of propeller 12. The nose cap isusually not a perfect cone, but is slightly rounded in overall contourto provide the best aerodynamic characteristics.

As is known in the art, nose cap 16 may be provided with cut outportions in the form of notches 30 on each side where the blade portions20 of propeller 12 extend from the spinner assembly. These notches maybe of various shapes, as illustrated for example in the patents citedabove, and the particular shape or size of these notches 30 is notcritical to the present invention. In fact, in view of the improvementof the present invention, as discussed below, it is not necessary thatnose cap 16 be provided with any notches 30 at all. Instead, nose cap 16could terminate short of the blade portions of propeller 12 so thatthere is a 360 opening between nose cap 16 and the engine housing notshown) of the model airplane.

Up to this point, the spinner assembly described is entirelyconventional. Moreover, all of the components of the spinner assembly 10may be made of conventionally used materials, including wood, metaland/or plastic. Although wooden propellers are still sometimes used inmodel airplanes, it is most common nowadays to use a relatively rigidthermoplastic such as polystyrene or polypropylene to form both thepropeller and the nose cap. While the propeller and nose cap should bemade of a material which is relatively rigid so as to withstandsubstantial distortion under normal stress conditions, the materialshould nevertheless be somewhat flexible and resilient in order toabsorb shock and the impact of crashes. The propeller shaft and threadednuts may be made of any suitable metal, but are preferably made of alightweight metal such as aluminum.

Turning to the improvement according to the present invention, nose cap16 is provided with a flange means 32 which extends from the innersurface of nose cap 16. As best shown in FIGS. 1 and 3, flange means 32comprises a cylindrical wall which extends parallel to the axis ofpropeller shaft 14, as well as the axis of conical nose cap 16.

Although flange means 32 has been shown as a continuous wall, it will beunderstood that a discontinuous flange could be used. However, acontinuous wall is preferred in order to provide the maximum rigidity tothe flange means 32. Moreover, it is preferred, as indicated in FIG. 1that the flange means 32 be molded integrally with the remainder of nosecap 16.

In the operating position of nose cap 16 (Le, when the spinner assemblyis completely assembled), the end 34 of flange means 32 remote from theinner surface of the nose cap 16 frictionally engages a shoulder means36 on starter nut 26. Shoulder means 36 comprises a right-angled ledgeformed by a first flange 38 and a second flange 40 on starter nut 26.First flange 38 extends radially to the axis of shaft 14 andperpendicular to the end 34 of flange means 32. Second flange 40projects generally perpendicularly from first flange 38 and generallyparallel to the cylindrical flange means 32. As a result, there isformed a shoulder means 36 which is frictionally engaged by flange means32, the end 34 of flange means 32 engaging the surface of first flange38 from which second flange 40 extends, and the outer cir cumference ofsecond flange 40 engaging the inner sur face of flange means 32.

In order to allow for a tight frictional or interference fit between theinner surface of flange means 32 and the outer surface of second flange40, it is preferred that the outer wall of flange 40 be rounded as shownat 42, so that flange means 32 may be slipped over second flange 40. Inaddition, second flange 40 is provided with holes 44 through which a barwrench or pin may be inserted in order to tighten starter nut 26 ontothe threaded portion 24 of propeller shaft 14.

As shown in FIGS. 1 and 2, starter nut 26 is provided with a base orpedastal portion 46 which abuts directly against hub portion 18 ofpropeller 12. Also, starter nut 26 is provided on the opposite side witha recess 48 formed by the inside surface of second flange 40. Recess 48need only be of sufficient diameter to permit turning of lock nut 28,and is preferably large enough to allow insertion of the socket of asocket wrench.

Lock nut 28 may be formed from a conventional cap nut. However,according to the present invention, the lock nut will have a threadedhole 50 provided in the cap portion of the lock nut 28. In the assembledposition, lock nut 28 is tightened against the starter nut 26 to preventstarter nut 26 from being backed off of the threaded portion 24 ofpropeller shaft 14, without first loosening lock nut 28. I

Nose cap 16 is then fastened to propeller shaft 14 by screw 52 whichthreads into the threaded hole 50 in the cap portion of lock nut 28.Screw 52 passes through a non-threaded hole 54 in the apex 56 of nosecap 16. If desired, the head 58 of screw 52 may be recessed into theapex 56 of nose cap 16, as shown in FIG. 1. After tightening screw 52the recess 60 may then be filled with a putty or rubber-like material,if desired, to form the tip or point of nose cap 16.

As screw 52 is tightened in threaded hole 50, the end 34 of flange means32 is forced tightly against shoulder means 36 on starter nut 26. Thiscreates a frictional fit between flange means 32 and shoulder means 36.As a result, when the cup 62 (shown in phantom in FIG. 1) of a startermotor is applied to the outer surface of nose cap 16, the entire spinnerassembly 10 is turned on shaft 14 to start the model airplane engine.

Since the rigid flange means 32 is capable of transmitting the torque ofthe starter motor to shaft 14 by means of the frictional engagement withshoulder means 36, there is relatively little stress and strain on theblade portions 20 of propeller 12, or on the relatively less rigidextremities of nose cap 16 adjacent notches 30 or on screw 52. Inaddition, flange means 32 provides more rigidity and reinforcement forthe outer surface of nose cap 16, so that nose cap 16 will not be dentedor pushed in by contact from the cup 62 of the starter motor.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention.

I claim:

1. In a spinner assembly for attachment to a threaded propeller shaft ofa model airplane comprising a propeller having hub and blade portions, agenerally conical, hollow nose cap, and first and second threaded nutsfor fastening said propeller to said threaded shaft, said first threadednut abutting against said propeller hub and said second threaded nutabutting against the opposite side of said first nut from said propellerhub, the improvement comprising flange means extending from the interiorsurface of said nose cap and shoulder means on said first threaded nut,said flange means frictionally engaging said shoulder means when saidnose cap is in operating position.

2. Apparatus according to claim 1 wherein said flange means comprises acylindrical wall, said cylindrical wall extending parallel to the axisof said threaded shaft.

3. Apparatus according to claim 2 wherein said shoulder means comprisesfirst and second flanges extending from said first threaded nut, saidfirst flange extending radially to the axis of said threaded shaft andsaid second flange extending from said first flange and generallyparallel to said cylindrical wall.

4. Apparatus according to claim 3 wherein said first and second flangesextend substantially around the entire circumference of said firstthreaded nut.

5. Apparatus according to claim 3 wherein the outer circumference ofsaid second flange is in frictional engagement with the inner surface ofsaid cylindrical wall.

6. Apparatus according to claim 3 wherein the end of said cylindricalwall remote from the inner surface of said nose cap frictionally engagesthe surface of said first flange from which said second flange extends.

7. Apparatus according to claim 1 wherein said second threaded nut is acap nut, said cap nut having aperture means in the cap portion thereoffor receiving fastening means from said nose cap.

8. Apparatus according to claim 7 wherein said nose cap has aperturemeans in the apex thereof for receiving fastening means.

9. Apparatus according to claim 8 wherein said nose cap is fastened tosaid propeller shaft by screw means extending through said aperturemeans in said nose cap and into threaded engagement with said aperturemeans in the cap portion of said cap nut.

10. Apparatus according to claim 9 wherein said flange means is forcedinto frictional engagement with said shoulder means by tightening saidscrew means.

11. Apparatus according to claim 1 wherein said nose cap is providedwith cut out portions whereby said blade portions of said propeller passthrough the walls of said nose cap.

12. Apparatus according to claim 11 wherein said out out portionscomprise notches in the walls of said nose cap remote from the apexthereof.

1. In a spinner assembly for attachment to a threaded propeller shaft ofa model airplane comprising a propeller having hub and blade portions, agenerally conical, hollow nose cap, and first and second threaded nutsfor fastening said propeller to said threaded shaft, said first threadednut abutting against said propeller hub and said second threaded nutabutting against the opposite side of said first nut from said propellerhub, the improvement comprising flange means extending from the interiorsurface of said nose cap and shoulder means on said first threaded nut,said flange means frictionally engaging said shoulder means when saidnose cap is in operating position.
 2. Apparatus according to claim 1wherein said flange means comprises a cylindrical wall, said cylindricalwall extending parallel to the axis of said threaded shaft.
 3. Apparatusaccording to claim 2 wherein said shoulder means comprises first andsecond flanges extending from said first threaded nut, said first flangeextending radially to the axis of said threaded shaft and said secondflange extending from said first flange and generally parallel to saidcylindrical wall.
 4. Apparatus according to claim 3 wherein said firstand second flanges extend substantially around the entire circumferenceof said first threaded nut.
 5. Apparatus according to claim 3 whereinthe outer circumference of said second flange is in frictionalengagement with the inner surface of said cylindrical wall.
 6. Apparatusaccording to claim 3 wherein the end of said cylindrical wall remotefrom the inner surface of said nose cap frictionally engages the surfaceof said first flange from which said second flange extends.
 7. Apparatusaccording to claim 1 wherein said second threaded nut is a cap nut, saidcap nut having aperture means in the cap portion thereof for receivingfastening means from said nose cap.
 8. Apparatus according to claim 7wherein said nose cap has aperture means in the apex thereof forreceiving fastening means.
 9. Apparatus according to claim 8 whereinsaid nose cap is fastened to said propeller shaft by screw meansextending through said aperture means in said nose cap and into threadedengagement with said aperture means in the cap portion of said cap nut.10. Apparatus according to claim 9 wherein said flange means is forcedinto frictional engagement with said shoulder means by tightening saidscrew means.
 11. Apparatus according to claim 1 wherein said nose cap isprovided with cut out portions whereby said blade portions of saidpropeller pass through the walls of said nose cap.
 12. Apparatusaccording to claim 11 wherein said cut out portions comprise notches inthe walls of said nose cap remote from the apex thereof.